Dresden Files RPG characters have a total of 7 permanent Aspects attached to them. Your High Concept and Trouble are usually the most important two, but you have 5 more to pick before you're done.
Basically you have 7 chances to cram as much into a short phrase as humanly possible.
The three most important characteristics of a great Aspect are (to me anyway):
- They must be clever (so everyone knows how clever I am!)
- They have to be something I can see using to help me out of a tight spot
- They have to make a GM rub their hands in glee at their prospects for Compelling.
Some aspects are going to be better at the second than the third, and some vice versa. I'll talk about that in a second.
Other important characteristics of a good Aspect:
- They have to express something essential about your character to the world.
- Ideally they sum up the phase that they come from.
- They need to be very distinct from all the other Aspects. This is a big one, no two Aspects should do the same thing, or you are severely handicapping yourself. This would be like taking Proficiency: Halberds and Proficiency: Guisarmes. Nice job wasting a feat. I'm showing my lack of D&D knowledge.
- They should have a strong context within the story. Having an Aspect that dealt with your desert survival skills isn't going to be that relevant to a game set in Albany, NY.
It's a good, solid practice to list a few potential Invoke and Compel situations for each of your Aspects. That makes sure you and the GM are on the same page as to what they mean. Don't try and list every situation, you aren't limited to what you think they mean now. Later on, in the heat of the action, you'll have a brilliant stroke of genius, and interpret the Aspect in a new way, and it will mean that too.
Invoking and Compelling Aspects: I don't remember if I've discussed this in detail before, so here we go (again?) Your player will occasionally need to haul out the heroic effort in order to succeed in a dramatic enough style to get the Russian Judge to drag the stick out of his hoo-ha and award you the gold. To do that, your character calls on the base elements that make him who he is, and spends a FATE point to Invoke an Aspect (or two, or three). In order for an Aspect to be Invoked to aid a cause, the Aspect has to directly relate to the effort you're putting in. "Blood of an Englishman" isn't going to be much use if you're trying to stay on your surfboard all the way through the tube. You may only Invoke one Aspect per FATE point you spend, but may spend as many FATE points as you have at any time. You really need to have great, flexible aspects, and you need a great imagination to explain why they apply to your situation. Any Invoking has to have the support of the GM and the other players, but in my experience if it sounds cool, it works.
Compelling is where the magic happens. You want your GM to read your Aspect and see all the different ways there are to hang you by your short hairs from it. If they are eager to Compel your Aspect, the FP will come flooding in. My Hockey Player has Zombie problems, but he's a good guy, and one of his Aspects is "I Have To Save Everyone I Can". Ttory, the GM, practically chortled when he saw it, and he is still obscenely gleeful whenever it comes up.